Inhibition of Electrolyte Oxidation in Lithium Ion Batteries with Electrolyte Additives

The incorporation of additives designed to sacrificially react on the surface of cathode materials in lithium ion batteries has been investigated. Addition of low concentrations of either 2,5-dihydrofuran or γ -butyrolactone to 1 M LiPF6 in 1:1:1 ethylene carbonate/diethyl carbonate/dimethyl carbonate improves the capacity retention of Li/Li 1.17Mn0.58Ni0.25O2 cells cycled at 4.9 V vs Li. A surface analysis of the cathode materials (X-ray photoelectron spectroscopy and IR) suggests that the structure of the cathode surface film is modified by the presence of the additives resulting in a decrease in detrimental electrolyte oxidation reactions on the cathode surface. © 2009 The Electrochemical Society.